code: def test_substitute(self):
      data = AudioLoader.load_mel_spectrogram(
          self.sample_wav_file, n_mels=self.num_of_freq_channel
      )
      aug = nas.TimeMaskingAug(stateless=False)
  
      aug_data = aug.augment(data)
      aug_audio = aug_data[0]
  
      self.assertEqual(
          len(data[:, aug.t0]), np.count_nonzero(data[:, aug.t0])
      )
      self.assertEqual(0, np.count_nonzero(aug_audio[:, aug.t0]))
  
file_path: nlpaug/test/augmenter/spectrogram/test_time_masking.py
imports: import unittest
  import os
  from dotenv import load_dotenv
  import numpy
  from nlpaug.util import AudioLoader
  import nlpaug.augmenter.spectrogram
label_desc: Use image node_id 3 for calling the TestTimeMasking obj's underlying member method code with example usage: obj.test_substitute() without return types